Typically the base stations in the current mobile networks use receiver diversity, i.e. the signal is received through 2 antennas or 1 antenna with 2 cross-polar receivers, combining the signals and obtaining a gain in coverage. This is applicable to the GSM, UMTS, LTE, WiMAX or any other cellular network.
More recently it has become feasible to offer 4 way receiver diversity, which gives more gain than the 2-way receiver at the expense of a higher processing overhead. As an example, in UMTS the gain can be of about 2.5 dB, improving the coverage and the throughput obtained in HSDPA due to the gain in the uplink.
In general terms, the disadvantage of multiple (x-way) receiver diversity technology is that the baseband consumption is very high as the signal has to be processed x/2 more times than with the 2 way. This means more baseband hardware needed in the base stations.
It is well-known that abbreviations and acronyms are frequently used in the mobile telephony field. Below is a glossary of acronyms/terms used throughout the present specification:    GSM Global System for Mobile Communications    LTE Long Term Evolution    CS Circuit Switched    PS Packet Switched    RNC Radio Network Controller    UMTS Universal Mobile Telecommunications System    HSDPA High Speed Downlink Packet Access    WiMAX Worldwide Interoperability for Microwave AccessSummary of Example Embodiments
Embodiments of the invention relate to methods and systems for controlling receiver diversity operation in a base station of a mobile telecommunications network.
In one example embodiment, a base station comprises a first receiver arrangement and a second receiver arrangement and is operated in accordance with steps, including:                activating the first receiver arrangement, thereby receiving signals at a first gain level;        activating the second receiver arrangement, thereby receiving signals at a second gain level, said second gain level being equal or lower than said first gain level;        measuring baseband consumption at the base station at predetermined intervals; and        if the baseband consumption exceeds a predetermined deactivation threshold THDE deactivating the first receiver arrangement, thereby leaving only the second receiver arrangement active.        
In a disclosed embodiment, the above method further comprises the following step:                if the baseband consumption goes below a predetermined activation threshold THAC, activating the first receiver, thereby receiving signals at an increased gain level in the base station.        
The first receiver arrangement can be a 4-way receiver arrangement and the second receiver arrangement can be a 2-way receiver arrangement.
The example method is thus an algorithm integrated in base stations. The algorithm allows a network to switch automatically between “normal” two-way receiver diversity operation and x-way receiver diversity operation based on the baseband occupation. For example, in case of congestion of the baseband resources it can switch from 4-way receiver to 2-way receiver.
One advantage lies in the way x-way diversity activation is automatic and dynamically related to the baseband occupation. It is thus possible to activate x-way receiver diversity without the need to add more baseband. As a result fewer baseband boards are required in every base station even when 4-way (or in general, x-way) receiver diversity operation is activated.
In an exemplary system the base station comprises a first receiver arrangement and a second receiver arrangement, wherein the first receiver arrangement is initially activated and thereby receiving signals at a first gain level, and the second receiver arrangement is activated and thereby receiving signals at a second gain level. The second gain level is equal or lower than said first gain level. In this example environment, the example system comprises a baseband unit configured for:                measuring baseband consumption at the base station at predetermined intervals, and        in case the baseband consumption exceeds a predetermined deactivation threshold THDE deactivating the first receiver arrangement, thereby leaving only the second receiver arrangement active.        
In a preferred embodiment the baseband unit is additionally configured for, in case the baseband consumption goes below a predetermined activation threshold THAC, activating the first receiver, thereby receiving signals at an increased gain level in the base station,
The first receiver arrangement is preferably a 2-way receiver arrangement and the second receiver arrangement is preferably a 2-way receiver arrangement.